48V Battery Management System

Battery management system for up to 15 Li-ion cells based on bq76940 or bq76930 IC from Texas Instruments

The Libre Solar BMS is divided into two different boards:

Control board (BMS48V)

Power board (Switch-N-Sense)

A picture of the current version is shown below:

On the bottom of the control board (left side), the cells are connected for balancing and voltage monitoring. In addition to that, up to three temperature sensors (10k thermistors) can be connected to the board. The board features a CAN interface through two daisy-chained RJ-45 connectors. Via the universal UEXT connector, additional peripherals can be connected via SPI, I2C or USART.

The Switch-N-Sense board acts as the interface between the Li-ion battery and the outside world. It contains the sense resistors for current measurement and charge/discharge MOSFETs at the bottom side. For improved cooling, it can be attached to a cooling plate. The wire-to-board connection is done via Würth Power Element press-fit connectors, allowing very high currents.

The two boards are separated in order to adjust the power part depending on your actual needs. If you only need to deliver low currents from the battery, the Switch-N-Sense board can be smaller and cheaper.

This repository contains only the control board. Please see the Switch-N-Sense repository for details on the power part of the BMS including hardware files.